Infectious Laryngotracheitis (ILT) in Chickens: Signs and Control

Is that bird gasping, or just coughing?

Some mornings the house sounds wrong before anything looks wrong. A flock with ILT is often quiet except for a few birds stretching their necks and making a rasping sound, like someone pulling air through a straw. A cold makes a bird sneeze. ILT makes it gasp, and the gasp is the sound you learn to recognise first.

Infectious laryngotracheitis, usually shortened to ILT, is caused by a herpesvirus that attacks the larynx and trachea, the voice box and windpipe at the top of the bird's airway. The infection does not stay on the surface. It causes swelling and bleeding inside the airway, and in bad cases the bird cannot get enough air through the narrowed tube.

ILT often appears after a farmer has added birds from a neighbour, a market or a mixed flock. It does not need a new flock to arrive, though. The virus can travel on a visitor's shoes, a reused crate or a bird that looked fine when it left the farm next door.

What the virus does in the windpipe

The virus invades the cells lining the trachea. Those cells swell, die and slough off, and the airway fills with a mix of mucus, blood and debris. A bird trying to breathe through a clogged, narrowed tube makes the gasping sound and stretches its neck to open the passage. You may see it shaking its head to clear the mucus, or see a dark streak on the beak and around the mouth.

The eyes can be affected too. Some birds develop watery or swollen eyes, because the infection can pass along the tear ducts to the conjunctiva. Look at the eyes of a sick bird as well as its airway.

After the acute stage some birds recover, but the virus does not always clear. It can stay latent in the nervous tissue and come back when the bird is stressed. A bird that seemed to get over it can be the source of trouble for the next flock on the same farm.

How it spreads on a Ghanaian farm

ILT spreads mostly through respiratory secretions. That means droplets from coughing or head-shaking birds, dried mucus on equipment, and the litter and crates that carry them. Birds that recover can shed the virus for a time, and carriers can sit inside a flock that looks perfectly healthy.

• Birds bought from a neighbour, a market or a mixed flock that nobody has checked.
• Visitors who walk from a sick house to yours without changing footwear.
• Crates, trays and feed sacks that have gone back and forth between farms.
• Sprayers, drinkers and feeders shared between pens or houses.
• Live vaccine that was handled carelessly, which can move from vaccinated birds to the rest of the flock.

In the markets, birds change hands quickly and nobody asks where they have been. That is exactly the movement that gives a virus a route onto a new farm. Our piece on biosecurity on a poultry farm sets out the steps that cut that risk.

Telling ILT from its look-alikes

Several diseases make birds cough or gasp, and a wrong guess wastes time. This comparison is the one we use when a farmer describes a problem over WhatsApp. It is a rough guide only and does not replace a vet's diagnosis.

Fowl pox can affect the throat in its wet form, so if you see scabs on the comb or wattles alongside breathing trouble, read our guide to fowl pox. For the facial swelling, our page on infectious coryza goes through the signs. Young birds with rattling breath can also point to infectious bronchitis, and slower cases fit chronic respiratory disease better.

The vaccine: what it does, and what it cannot do

ILT vaccines are live. The virus in the vaccine is weakened, and it is given through the eye, the drinking water or a spray, depending on the product and on what your vet recommends. Live vaccines work well in the right birds at the right time, but they carry two risks that farmers need to understand.

The first is the reaction. Some vaccinated birds develop the same airway signs the vaccine was meant to prevent. In a well-run flock these are usually mild and short, but they can be worse in birds that are already sick or stressed. The second is spread. Vaccine virus can move from vaccinated birds to unvaccinated ones, especially in a shared house or through shared equipment. A flock that was vaccinated can still show signs if the vaccine was handled badly.

A common pattern in Ghanaian pullet programmes is a live vaccine given at around 10 to 12 weeks, ahead of point of lay. Treat that as an example of timing, not a schedule to copy. Your vet will set the timing for your birds, the products available in Ghana and the risk on your farm.

Handling matters as much as timing. Use clean, dedicated equipment, keep the vaccine cold as the label says, and vaccinate in a quiet, closed room early in the morning. Do not use the same sprayer or bucket on sick birds. Record the batch number, the date and the number of birds vaccinated, so that any reaction can be traced.

What ILT costs in a laying house

Layers lose most through egg drop rather than deaths, so do the sum on eggs. Take a house of 400 hens. Our table eggs sell at 50 GH₵ per crate of 30, which works out to about 1.67 GH₵ per egg. If ILT cuts lay by 15 per cent for three weeks, the house loses 60 eggs a day, or 1,260 eggs in total. At our crate price that is roughly 2,100 GH₵ in lost eggs, before any treatment, extra labour or birds that die.

Add the deaths, which can be higher in older birds, and the bill climbs quickly. A house showing signs should see a vet within two days, not after the drop has dragged on for a month. Every day of delay is a day of eggs that will not come back.

Biosecurity that stops a spread

Most of the control on a farm comes down to not carrying the virus in on your clothes, tools and birds. Biosecurity is dull work, and it is the work that works.

1. Keep a clean line at the gate, with a footbath and a change of footwear for anyone who enters the houses.
2. Do not let visitors walk from another poultry house straight into yours.
3. Quarantine new birds away from the flock for a period your vet agrees, and watch them every day.
4. Wash and dry crates, trays and sacks before they go back out or come back in.
5. Keep sprayers, drinkers and feeders separate for each house, and disinfect them between uses.
6. Remove dead birds promptly and dispose of them the way your vet advises.

Our article on quarantining new birds explains how long to keep them apart and where. If you run your farm on all-in all-out, our note on the all-in all-out system explains why an empty gap between flocks helps against diseases like this one.

Dust, ammonia and the harmattan

The harmattan is the season when airway trouble gets worse across the board. The dust that blows down from the north dries out the lining of the airways and gives viruses an easier way in. Dust also carries the virus on particles that settle on litter and equipment, which keeps it moving through a house long after the birds have been moved.

Cut the dust by keeping the top of the litter lightly damp, sweeping the feeder area with a damp broom, and avoiding dry sweeping inside the house while birds are present. Keep ammonia down with the same airflow and litter routine you use in the rainy season. The aim is air that is not dusty, not damp and not stale, at bird level, with enough movement to clear the smell without a draught on the birds.

Recovered birds: the carriers you cannot see

A bird that recovers from ILT is not automatically safe. Some birds carry the virus for months, often with no signs at all, and stress can bring the infection back. On a mixed farm the rule we give is simple: keep the ages separate, and keep any bird that has been sick away from the younger flock until your vet says otherwise.

What we often see on farms with repeat trouble is a second flock bought in, a few birds kept back from an old house, or pullets raised next to older hens. Each of those is a chance for a carrier to meet a susceptible bird. Clean and empty the houses between flocks, and do not move litter or equipment from an old flock into a new one.

A checklist for this week

If you suspect ILT, work through this list in order and call your vet before you finish the first morning.

1. Listen at first light and count the birds that gasp or stretch their necks.
2. Look at the eyes and beak of any bird that is struggling, and note the discharge.
3. Count the eggs for three days in a row and write the numbers down.
4. Check the footbath, the gate and the footwear of every visitor.
5. Separate the sick birds and give them their own tools.
6. Call your vet the same day, and give them the ages, the numbers and the egg counts.
7. Write down the batch and date of every live vaccine given this season.

Follow your vet's advice on any treatment or vaccine. Antibiotics do not kill viruses, although a vet may use them to control a secondary bacterial infection.

What we can and cannot do about ILT

The hatchery covers Marek's, Newcastle, Gumboro, infectious bronchitis and coccidiosis before a chick leaves us. ILT is not on that list, so ask your vet whether a live ILT vaccine should be given on your farm, and when, for your flock.

If you are planning layers and want the timing right, the pullet stage is the time to talk to your vet. We can help you plan the order and the dates on WhatsApp at +233 24 915 1503. Our layer day-old chicks page explains the breeds we supply, and our breed notes compare them side by side.

We will not promise that a chick from our hatchery can never carry or catch ILT. What happens after the box leaves our hands depends on your house, your visitors and your vet's programme, and most of that is in your control.

Questions farmers ask